Could Rickon really have lifted an old rusted iron sword from the crypts? Aren’t they really heavy?

This is a fantasy/genre/movie misconception. 

Swords are not heavy, contrary to every D&D equipment section ever, because IRL they are relatively thin pieces of metal meant to cut things. Even the heaviest swords, those giant two-hand swords that people used to hack through pike formations and cut the legs off of horses, weigh less than 7 pounds. Your average sword weighs more like 2.5-3.5 pounds. Rickon Stark could certainly lift one.

Control would be a different issue. Having held my fair share of swords when I was a kid, it wasn’t difficult to lift one, but it was very difficult to use in an effective fashion, both because kids don’t have great hand-eye coordination to begin with, nor do they have the proper leverage due to their height, weight, length of arms, etc. 

So I would imagine Rickon would find said sword very unwieldy. He would be dragging it along the ground, it would catch and snag on everything, he would probably drop it a lot, and any swings would go wildly off course and quite likely cause him to fall over.

This may be my most nerdy post ever.